1. Field of the Invention
This invention relates to devices for adjusting the lateral position of a moving belt. In one aspect, the invention relates to a belt positioning assembly for automatically adjusting the position of a belt during operation of a belt filter press.
2. Description of the Related Art
Belt filter presses are utilized to remove liquid from a mixture of liquid and solid material, leaving a relatively dry, solid xe2x80x9ccakexe2x80x9d for disposal or further processing. The belt filter press comprises a frame and an assembly of rollers that support and drive an upper continuous belt and a lower continuous belt that are in operable communication with each other. The belts are permeable to allow the extrusion of the liquid therethrough. The mixture is first placed on the lower belt, then xe2x80x9csandwichedxe2x80x9d between the upper and lower belts. The belts and the retained mixture then pass through a wedge section where the mixture is evenly distributed between the belts, and an initial volume of liquid is removed. The belts then pass through a series of progressively smaller diameter rollers where the retained mixture is compressed for further liquid removal. The belts are then separated and the dry xe2x80x9ccakexe2x80x9d is removed from the belts, generally by a scraping apparatus. The belts then pass through one or more belt washers, after which the process is repeated. The liquid from the extrusion and belt washing processes are collected for disposal.
The belts must remain in alignment relative to the rollers and to each other for proper filter press operation and dewatering of the material. The belts are typically aligned at the beginning of the operation. Any misalignment that occurs during operation of the filter press generally necessitates a shutdown of the filter press so that the belts can be realigned.
The invention comprises a device for adjusting the lateral position of an endless belt. It includes a sensor for detecting the lateral position of an endless belt relative to a predetermined position; a roller disposed adjacent to the endless belt; a controller operatively connected to the sensor and to the roller, and an air bellows operably connected to the controller to move the roller laterally in response to a signal from the controller. The volume of air in the bellows is controlled by an air valve and the controller signals the air valve to open and close to adjust the air volume in the air bellows so that the controller will automatically cause the roller to urge the endless belt toward the predetermined position when the sensor detects that the lateral position of the endless belt is away from the predetermined position. Preferably, the sensor comprises an inductive proximity transducer and comprises a wheel disposed against an edge of the belt in rotational communication therewith. The sensor signals the lateral position of the endless belt to the controller, which is preferably a computer.
In another aspect of the invention, a device for adjusting the lateral position of an endless belt disposed to move over a roller in a given direction comprises a sensor for detecting the lateral position of the endless belt relative to a predetermined position; an air bellows operably connected to at least one end of the roller in a position to adjust the position of the roller relative to the belt by expansion or contraction of the bellows; and a controller operatively connected to the sensor and to the air bellows. The controller will automatically cause the air bellows to expand or contract, thereby adjusting the position of the roller to urge the endless belt toward the predetermined positioned when the sensor detects that the lateral position of the endless belt is away from the predetermined position.
The air bellows urges the one end of the roller to move in the given direction to cause the belt to move laterally relative to the roller. In this case, the air bellows is positioned in the given direction. There can be a first air bellows and a second air bellows, where the second air bellows is positioned in the given direction opposite the one end of the roller from the first air bellows. Either way, an air valve is preferably positioned between the controller and the air bellows, and the controller automatically causes the air bellows to expand or contract by signaling the air valve.